Genetic regulatory signals in the Escherichia coli chromosome are DNA sequences which are recognized by specific proteins in a manner which determines whether or not the associated gene groups are expressed. Using the lactose operon promoter as a model system, we plan to analyze how specific parts of the sequence influences the cognitive RNA polymerase - promoter interaction. This will be accomplished by generating changes at as many sites as possible in the promoter, defining the steps in the RNA polymerase - promoter interaction and then determining how different changes in the sequence affect different steps. Antibiotic resistance in bacteria is frequently determined by genes carried on transposable genetic elements termed transposons. We are interested in analyzing the genetic organization of two of these transposons, Tn5 and Tn10. These studies will include analyzing the location and orientation of genes encoding antibiotic resistance, Tn5 transposition functions, and, in the case of Tn10, regulation of antibiotic resistance functions. The controlling elements for these genes will be defined and sequenced.